HARARE, Zimbabwe, Aug. 2 (UPI) -- Presidential and parliamentary elections this week in Zimbabwe were free and credible, the head of the African Union's observer mission said Friday.

Olusegun Obasanjo said certain "incidents" reported during Wednesday's polling could not "change the outcome" even though the largest observer group called the elections "seriously compromised," the BBC reported.

President Robert Mugabe's party claimed victory in the election that challenger Prime Minister Morgan Tsvangirai called a "huge farce."

Obasanjo, speaking in Harare, said the elections were "free, honest and credible."

He said there were "incidents that could have been avoided," but stressed that African Union monitors did not think they would change the elections' overall outcome, the BBC reported.

The "incidents" were not described.

In contrast, the Zimbabwe Election Support Network said Thursday the elections were "seriously compromised," with up to 1 million people unable to vote.

First official results from National Assembly elections indicate Mugabe's Zanu-PF party staked an early lead, but the parliamentary results announced were mainly from his strongholds in rural areas.

Zanu-PF spokesman Rugaro Gumbo predicted Mugabe -- seeking his seventh term -- would pick up at least 70 percent of the vote in a "landslide victory."

Voters cast ballots for president, 210 lawmakers and local councilors.

Under Zimbabwe's electoral law, if no one gains 50 percent of the vote, a runoff will be Sept. 11.

Zanu-PF and Tsvangirai's Movement for Democratic Change shared governance since 2009 under a brokered deal ending the violence that broke out in the aftermath of the 2008 presidential election.

Zimbabwe's main industries are platinum, diamond, and gold mining, as well as agriculture, but the nation has been difficult to do business with since Mugabe's government confiscated farms and nationalised industries, taxing private enterprise heavily while subsidizing government producers.